Microsoft has updated Windows to require users to create and configure a PIN for FIDO2 security keys during sign-in, even if they did not set one during initial registration. This requirement applies to users who install the Windows preview update released on September 29, 2025 (KB5065789, OS Builds 26200.6725 and 26100.6725) or later updates. The necessity for a PIN is triggered when a Relying Party (RP) or Identity Provider (IDP) requests User Verification set to “Preferred.” The update aims to ensure compliance with WebAuthn specifications and began rolling out gradually on Windows 11 devices after the September 29, 2025 update, with full deployment completed by the November 11, 2025 security update (KB5068861, OS Builds 26200.7171 and 26100.7171). Windows now supports three verification settings: Discouraged, Preferred, and Required, with “Preferred” indicating that user verification should occur if supported by the authenticator.